Fiber optic headlights are worn on the head of surgeons, technicians, and like individuals for directing a spotlight beam of intense light coincident with the wearer's line of sight, independent from overhead and/or ambient lighting. The headlights include a headlamp that receives an emitting end of a fiber optic cable and that focuses and directs the light from the cable into a beam aimed forward of the wearer. The headlamp includes an assembly of optic elements that is preferably configured in a tubular elbow which depends from a headset, or headband, at the wearer's forehead to a location approximately between the wearer's eyes.
A typical headlamp receives a male end tip of the fiber optic cable in a port having a captive, spring-wire snap-ring that engages a circumferential groove on the end tip and thereby holds the end tip in a fixed position relative to the optics in the headlamp. The divergent light emitted by the end tip is directed through a convergent lens, or lens system, and iris diaphragm (if so equipped) to a mirror where it is reflected forward through a final lens. The visual characteristics of the light beam projected by the headlamp are determined by the entire train of components from the initial light source to the emitting lens of the headlamp. Typically, the only controls with respect to the projected light are brightness, which is effected by a moveable shutter incorporated in the light source cabinet, and the size of the spot of light on a surface at a predetermined distance from the headlamp, which is effected by adjusting the iris orifice (if so equipped) within the headlamp.
If the optical system of the headlight is perfectly focused, the projected beam carries an undesirable image of the assembled fibers at the emitting surface of the end tip thereby producing a dense honeycomb of shadows between the individual fibers. The projected beam will also carry an undesirable image of any small particles of dust which may be present on any of the optics. To alleviate these problems, the optic system is intentionally slightly defocused to blend such images away from visibility. However, this is a sensitive technique, since defocusing also causes undesirable rings and haloes of light and shadows to appear in the projected beam and spot of light, and the overall brightness of the beam and spot of light diminishes.
Different models of headlights produce different spot diameters and different distributions of light within the spot. Typically, two styles of light distribution are utilized. One is a sharply defined spot having even brightness throughout. The other is a less sharply defined spot having intense brightness in the interior of the spot fading off toward the peripheral outer edges of the spot. Both styles are functions of the degree to which the optic system is defocused. Users of headlights have personal preferences which may depend upon particular operating conditions.
Examples of headlight systems are provided by U.S. Pat. Nos. 5,430,620 issued to Li et al.; 3,285,242 issued to Wallace; 5,709,459 issued to Gourgouliatos; 5,774,271 issued to Lagerway et al.; 6,224,227 issued to Klootz; 6,120,161 issued to Van Der Bel; 5,769,523 and 3,745,993 issued to Feinbloom; 4,616,257 and 4,797,736 issued to Kloots et al.; 4,516,190, 4,104,709 and 3,951,139 issued to Kloots; and 4,290,422 issued to Burton. U.S. Pat. No. 5,268,977 issued to Miller is directed to a fiber optic luminaire.
Although the aforementioned headlights may function in a satisfactory manner for their intended purposes, there is a need for a headlight system that enables ready adjustability of beam quality. For instance, the headlight system preferably should permit the distribution of light within a light beam and spot to be readily altered in a convenient and uncomplicated manner and without having to alter the diameter of the beam or spot. In addition, the headlight system should preferably provide a kit, or family, of different readily interchangeable parts all constructed from similar or the same components to enable the user to produce a desired spot size and/or spot style within a range of choices.